4) You\'ve built a hyper biofuel producing strain and to prevent corporate espio
ID: 145615 • Letter: 4
Question
4) You've built a hyper biofuel producing strain and to prevent corporate espionage you have incorporated a kill switch using CRISPR that destroys your host genome when triggered (a real issue! - Caliendo & Voigt, Nat Comm doi:10.1038/ncomms7989). You create a system that represses death under lab conditions (a blend of magic nutrients) but will be triggered outside of the lab when these nutrients are absent a) How would you design your gene regulation to definitively_determine cell fate and ensure accurate triggering of your kill switch? [2 points] b) Your design initiates cell death when a key repressor protein is unable to bind DNA. This protein binds only in the presence of your magic nutrient, which, unfortunately, is present in the environment at low levels. How would you shift/transform the input-output relationship to ensure that the system is triggered when not present in lab conditions of high nutrient? It may help to draw the Hill functions [3 points] c) What parameters would you actually control to effect this change? How would you physically implement this? [5 points]Explanation / Answer
a) Killing the bacteria, necesserily doesnt mean can eliminate all the DNA/plasmids. As these are biofuel producing strains, releasing these DNA may easily become recombinant DNA and may have adverse effect. Hence, acurately destroying the DNA/plasmids paly an important role.
The system should contain a CRISPR targeting a DNA/RNA (most prefered target would be RNA, that would directly destrut a gene) and an apoptotic protein (here we would assume Cas9 that can excercise the DNA/gene). This protein is controlled by a promoter that will activate the gene when a particular antibiotic/nutrient is present (Say arabinose).
Now in the presence of arabinose in the medium, the bacterial cells will edit out all the plasmids. This CRISPR-Cas9 is the most studied kill switch system.
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